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•� n <br /> ATTACHMENT A <br /> FIELD AND LABORATORY PROCEDURES <br /> Sampling Procedures <br /> Sampling equipment is thoroughly cleaned prior to each sample The sampling procedure for each well <br /> includes measuring the water level and checking for the presence of liquid-phase hydrocarbons (LPH), <br /> using either an electronic indicator and a clear Teflon@ bailer or an oil-water interface probe Wells not <br /> containing LPH that do not have submerged screens are then sampled without purging Wells that have <br /> submerged screens are purged of approximately three casing volumes of water (or to dryness) using a <br /> clean submersible pump, centrifugal pump, gas displacement pump, or bailer The equipment and <br /> purging methods used for the current sampling event are noted on the attached field data sheets During <br /> purging, temperature, pH, and electrical conductivity are monitored in order to document that these <br /> parameters are stable prior to collecting samples After purging, water levels are allowed to partially <br /> recover Groundwater samples (both purge and no-purge) are collected using a clean Teflon® bailer, <br /> placed into appropriate EPA-approved containers, labeled, logged onto chain-of-custody documents, and <br /> transported on ice to a California state-certified laboratory <br /> Laboratory Procedures <br /> The groundwater samples are analyzed for the presence of TPHg, benzene, toluene, ethylbenzene, <br /> xylenes (total), and MtBE using EPA Methods 8015 (modified) and 8021, and fuel oxygenates using EPA <br /> Method 8260B The methods of analysis for the groundwater samples are documented in the certified <br /> laboratory analytical report The certified laboratory analytical report, chain-of-custody documentation, and <br /> • field data sheets are presented as Attachment B <br /> Purge and Rmsate Water Disposal <br /> Water generated during well sampling and equipment cleaning is pumped into a SECOR truck-mounted <br /> water tank The water is transported to ARCO's holding facility in West Sacramento, California, for <br /> temporary storage Water is then transported by Integrated Waste Management (IWM) to Seaport <br /> Environmental in Redwood City, California for disposal <br />